Preoperative Planning Data Research Articles

Ultrasound-navigated laparoscopic liver surgery

Purpose: Actually the technique of laparoscopic liver resection has been mostly performed in high volume centers with hepatobiliary and laparoscopic expertise in highly selected patients. For better intraoperative visualization we developed a laparoscopic navigation system (LapAssistent) to register preoperative 3D-CT or MRI Scans to the intraoperative field. Intraoperative the laparoscopic instruments were connected to the LapAssistent with real-time ultrasound B-Mode screen and real-time laparoscopic video screen. Material and methods: Preoperative planning data were performed by Fraunhofer MeVis Bremen/Germany. After calibration of the system including camera, laparoscopic instruments and the intraoperative ultrasound probe we registered the surface of the liver. By the navigated ultrasound the preoperatively planned resection plane has then been overlain with the patient's liver. The laparoscopic navigation system has been able to use under sterile conditions and it has been possible to register and visualize the preoperative planned resection plane. Results: After experimental development of the navigation system we started in January 2010 with the clinical use of navigation-assisted laparoscopic liver surgery. We report about the technical aspects of the navigation system and the clinical use in three cases. One patient with a large benign adenoma was resected by laparoscopic navigated atypical liver resection. By a metastatic mammacarcinom one thermal ablation was done and in a third case two atypical resections in the right liver lobe. Conclusion: By the navigated ultrasound the preoperatively planned resection plane has then been overlain with the patient's liver. The laparoscopic navigation system has been able to use under sterile conditions and it has been possible to register and visualize the preoperative planned resection plane. These first results now have to be proven in a larger patient collective and we performed a German wide multicenter study (ProNavic I).

Study of application of surgical navigation assist oral and maxillofacial surgery based on 104 cases

Background and objectives: The temporomandibular joint plays a very important role for the function of the mandible. The delicate and complex anatomy of TMJ area challenges for the reconstructive surgery of this region. The objective of this study is to verify the feasibility and the effectiveness of the intraoperative image-guide navigation for the TMJ surgery. Methods: 45 Patients with TMJ diseases are enrolled in this study, including 30 cases with TMJ ankylosis, 10 with TMJ osteochondorma and 5 with post-surgical deformities due to TMJ ankylosis. The preoperative radiologic examinations involved thin-cut (0.625-mm) spiral CT scans for all patients. Using the DICOM protocol CT data sets, a virtual 3D skull model was created in navigation system TBNavis-CMFS (Shanghai, China). The preoperative individual planning and simulation data sets, including the generation of virtual models with TMJ arthroplasty (gap surgery) in 30 cases, articular fossa remodeling in 4 cases, condylar-ramus unit (CRU) reconstruction with rib graft in 1 cases, endoscopic-assisted osteochondroma resection/condylectomy in 10 cases, were used as a virtual template to guide surgical correction of those deformities by intraoperative instrumentand/or probe-based navigation. Results: Using 4–5 invasive markers for registration, an accurate match between the intraoperative actual position and 3-dimensional virtual model was achieved within a systematic error of 1 mm difference. With the guidance of the real-time navigation system, all the surgical procedures went on smoothly. The average deviation of the morphologic change after surgical correction was less than 1.5 mm with superimposing the preoperative planning and postoperative CT images. The followup evaluation showed that the clinical complaint symptoms were alleviated, and the postoperative function and esthetics improved remarkably. Conclusions: Navigation-guided surgery in the TMJ region provides better precision and safety for the surgeons and can be regarded as an ideal and valuable option for this potentially complicated procedure.

Navigation assisted temporomandibular joint reconstructive surgery

Background and objectives: The temporomandibular joint plays a very important role for the function of the mandible. The delicate and complex anatomy of TMJ area challenges for the reconstructive surgery of this region. The objective of this study is to verify the feasibility and the effectiveness of the intraoperative image-guide navigation for the TMJ surgery. Methods: 45 Patients with TMJ diseases are enrolled in this study, including 30 cases with TMJ ankylosis, 10 with TMJ osteochondorma and 5 with post-surgical deformities due to TMJ ankylosis. The preoperative radiologic examinations involved thin-cut (0.625-mm) spiral CT scans for all patients. Using the DICOM protocol CT data sets, a virtual 3D skull model was created in navigation system TBNavis-CMFS (Shanghai, China). The preoperative individual planning and simulation data sets, including the generation of virtual models with TMJ arthroplasty (gap surgery) in 30 cases, articular fossa remodeling in 4 cases, condylar-ramus unit (CRU) reconstruction with rib graft in 1 cases, endoscopic-assisted osteochondroma resection/condylectomy in 10 cases, were used as a virtual template to guide surgical correction of those deformities by intraoperative instrumentand/or probe-based navigation. Results: Using 4–5 invasive markers for registration, an accurate match between the intraoperative actual position and 3-dimensional virtual model was achieved within a systematic error of 1 mm difference. With the guidance of the real-time navigation system, all the surgical procedures went on smoothly. The average deviation of the morphologic change after surgical correction was less than 1.5 mm with superimposing the preoperative planning and postoperative CT images. The followup evaluation showed that the clinical complaint symptoms were alleviated, and the postoperative function and esthetics improved remarkably. Conclusions: Navigation-guided surgery in the TMJ region provides better precision and safety for the surgeons and can be regarded as an ideal and valuable option for this potentially complicated procedure.

Projector-based surgeon–computer interaction on deformable surfaces

Providing intuitive and easy to operate interaction for medical augmented reality is essential for use in the operating room. Commonly, intra-operative navigation information is displayed on an installed monitor, requiring the operating surgeon to change focus from the monitor to the surgical site and vice versa during navigation. Projector-based augmented reality has the potential to alleviate this problem. The aim of our work is to use a projector for visualization and to provide intuitive means for direct interaction with the projected information. A consumer-grade projector is used to visualize preoperatively defined surgical planning data. The projection of the virtual information is possible on any deformable surface, and the surgeon can interact with the presented virtual information. A Microsoft Kinect camera is used to capture both the surgeon interactions and the deformations of the surface over time. After calibration of projector and Kinect camera, the fingertips are localized automatically. A point cloud surface representation is used to determine the surgeon interaction with the projected virtual information. Interaction is detected by estimating the proximity of the surgeon's fingertips to the interaction zone and applying projector-Kinect calibration information. Interaction is performed using multi-touch gestures. In our experimental surgical scenario, the surgeon stands in front of the Microsoft Kinect camera, while relevant medical information is projected on the interaction zone. A hand wave gesture initiates the tracking of the hand. The user can then interact with the projected virtual information according to the defined multi-touch-based gestures. Thus, all information such as preoperative planning data is provided to the surgeon and his/her team intra-operatively in a familiar context. We enabled the projection of the virtual information on an arbitrarily shaped surface and used a Microsoft Kinect camera to capture the interaction zone and the surgeon's actions. The system eliminates the need for the surgeon to alternately view the surgical site and the monitor. The system eliminates unnecessary distractions and may enhance the surgeon's performance.

Comparison of manual rasping and robotic milling for short metaphyseal-fitting stem implantation in total hip arthroplasty: a cadaveric study

Objective: The ROBODOC system offers the theoretical advantage of providing better fit and mechanical stability of the stem in total hip arthroplasty. However, there has been no previous study on short metaphyseal-fitting stem implantation using the ROBODOC system. The aim of the present study was to compare the implant position and primary stability of short metaphyseal-fitting stems implanted by robotic milling and manual rasping in a human cadaveric femoral model.Methods: Eight matched pairs of human cadaveric femora were randomly assigned to a robotic milling group or manual rasping group. Operative time and intraoperative femoral fractures were monitored, and radiographic evaluation of stem alignment was performed by comparison of preoperative planning and postoperative CT data. Stability testing was performed on six matched pairs of femora, excluding two specimens in which intraoperative fractures occurred.Results: The robotic milling procedures took an average of 27 minutes longer than the manual rasping procedures (p < 0.001). The robotic milling group exhibited significantly better anteroposterior alignment and vertical seating, and also showed a significantly reduced variability in both alignment and vertical seating. No intraoperative femoral fracture was detected in the robotic milling group, whereas two femoral fractures and one femoral stem tip perforation were detected in the manual rasping group. Stability testing showed no significant difference in translational and rotational migrations between the two groups, although the robotic milling group showed a trend towards reduced variability of stability.Conclusions: Our cadaveric study suggests that the use of the ROBODOC system for short metaphyseal-fitting stem implantation may have advantages in improving implant fit and reducing the risk of intraoperative femoral fractures without compromising primary stability.

Laparoscopic Navigated Liver Resection: Technical Aspects and Clinical Practice in Benign Liver Tumors

Laparoscopic liver resection has been performed mostly in centers with an extended expertise in both hepatobiliary and laparoscopic surgery and only in highly selected patients. In order to overcome the obstacles of this technique through improved intraoperative visualization we developed a laparoscopic navigation system (LapAssistent) to register pre-operatively reconstructed three-dimensional CT or MRI scans within the intra-operative field. After experimental development of the navigation system, we commenced with the clinical use of navigation-assisted laparoscopic liver surgery in January 2010. In this paper we report the technical aspects of the navigation system and the clinical use in one patient with a large benign adenoma. Preoperative planning data were calculated by Fraunhofer MeVis Bremen, Germany. After calibration of the system including camera, laparoscopic instruments, and the intraoperative ultrasound scanner we registered the surface of the liver. Applying the navigated ultrasound the preoperatively planned resection plane was then overlain with the patient's liver. The laparoscopic navigation system could be used under sterile conditions and it was possible to register and visualize the preoperatively planned resection plane. These first results now have to be validated and certified in a larger patient collective. A nationwide prospective multicenter study (ProNavic I) has been conducted and launched.

Erratum to: TREK: an integrated system architecture for intraoperative cone-beam CT-guided surgery

Purpose A system architecture has been developed for integration of intraoperative 3D imaging [viz., mobile C-arm cone-beamCT (CBCT)]with surgical navigation (e.g., trackers, endoscopy, and preoperative image and planning data). The goal of this paper is to describe the architecture and its handling of a broad variety of data sources in modular tool development for streamlined use of CBCT guidance in application-specific surgical scenarios. Methods The architecture builds on two proven open-source software packages, namely the cisst package (Johns Hopkins University, Baltimore, MD) and 3D Slicer (Brigham and Women’s Hospital, Boston,MA), and combines data sources common to image-guided procedures with intraoperative A. Uneri Department of Computer Science, Johns Hopkins University, Traylor Building, Room #726, 720 Rutland Avenue, Baltimore, MD 21205-2109, USA e-mail: ali.uneri@jhu.edu S. Schafer · S. Nithiananthan Department of Biomedical Engineering, Johns Hopkins University, Traylor Building, Room #726, 720 Rutland Avenue, Baltimore, MD 21205-2109, USA e-mail: sebastian.schafer@jhu.edu S. Nithiananthan e-mail: sajendra@jhu.edu D. J. Mirota Department of Computer Science, Johns Hopkins University, 224 NEB, 3400 N. Charles Street, NE Baltimore, MD 21218, USA e-mail: dan@cs.jhu.edu 3D imaging. Integration at the software component level is achieved through language bindings to a scripting language (Python) and an object-oriented approach to abstract and simplify the use of devices with varying characteristics. The platform aims to minimize offline data processing and to expose quantitative tools that analyze and communicate factors of geometric precision online. Modular tools are defined to accomplish specific surgical tasks, demonstrated in three clinical scenarios (temporal bone, skull base, and spine surgery) that involve a progressively increased level of complexity in toolset requirements. Results The resulting architecture (referred to as “TREK”) hosts a collection of modules developed according to application-specific surgical tasks, emphasizing streamlined Y. Otake Department of Computer Science, Johns Hopkins University, 128 Hackerman Hall, 3400 N. Charles Street, NE Baltimore, MD 21218, USA e-mail: otake@jhu.edu R. H. Taylor Department of Computer Science, Johns Hopkins University, 127 Hackerman Hall, 3400 N. Charles Street, NE Baltimore, MD 21218, USA e-mail: rht@jhu.edu J. H. Siewerdsen Department of Computer Science, Johns Hopkins University, Baltimore, MD, USA J. H. Siewerdsen (B) Department of Biomedical Engineering, Johns Hopkins University, Traylor Building, Room #718, 720 Rutland Avenue, Baltimore, MD 21205-2109, USA e-mail: jeff.siewerdsen@jhu.edu

Navigation-Guided Correction of Midfacial Post-Traumatic Deformities (Shanghai Experience With 40 Cases)

To evaluate the effectiveness of navigation-guided surgical correction as the treatment of midfacial post-traumatic deformities. A total of 40 patients with midfacial post-traumatic deformities from 2007 to 2010 were involved in the present study. The preoperative planning and simulation data sets, including the generation of virtual models with the mirror tool, were used as a virtual template to guide surgical correction of those deformities by intraoperative instrument- and/or probe-based navigation. The outcome was checked by both superimposing the postoperative 3-dimensional computed tomography model on the preoperative planning model and clinical examination. Through registration, an accurate match between the intraoperative actual position and 3-dimensional virtual model was achieved with a systematic error of 1 mm difference. With the guidance of the navigation system, the average deviation of the morphologic change after surgical correction was less than 1 mm according to the image comparison between the preplanned and postoperative computed tomography. The 1- to 2-year follow-up evaluation showed that the clinical complaint symptoms were alleviated, and the postoperative function and esthetics improved remarkably. Navigation-guided correction in the treatment of midfacial post-traumatic deformities can be regarded as an ideal and valuable option for this potentially complicated procedure.

TREK: an integrated system architecture for intraoperative cone-beam CT-guided surgery.

A system architecture has been developed for integration of intraoperative 3D imaging [viz., mobile C-arm cone-beam CT (CBCT)] with surgical navigation (e.g., trackers, endoscopy, and preoperative image and planning data). The goal of this paper is to describe the architecture and its handling of a broad variety of data sources in modular tool development for streamlined use of CBCT guidance in application-specific surgical scenarios. The architecture builds on two proven open-source software packages, namely the cisst package (Johns Hopkins University, Baltimore, MD) and 3D Slicer (Brigham and Women's Hospital, Boston, MA), and combines data sources common to image-guided procedures with intraoperative 3D imaging. Integration at the software component level is achieved through language bindings to a scripting language (Python) and an object-oriented approach to abstract and simplify the use of devices with varying characteristics. The platform aims to minimize offline data processing and to expose quantitative tools that analyze and communicate factors of geometric precision online. Modular tools are defined to accomplish specific surgical tasks, demonstrated in three clinical scenarios (temporal bone, skull base, and spine surgery) that involve a progressively increased level of complexity in toolset requirements. The resulting architecture (referred to as "TREK") hosts a collection of modules developed according to application-specific surgical tasks, emphasizing streamlined integration with intraoperative CBCT. These include multi-modality image display; 3D-3D rigid and deformable registration to bring preoperative image and planning data to the most up-to-date CBCT; 3D-2D registration of planning and image data to real-time fluoroscopy; infrared, electromagnetic, and video-based trackers used individually or in hybrid arrangements; augmented overlay of image and planning data in endoscopic or in-room video; and real-time "virtual fluoroscopy" computed from GPU-accelerated digitally reconstructed radiographs (DRRs). Application in three preclinical scenarios (temporal bone, skull base, and spine surgery) demonstrates the utility of the modular, task-specific approach in progressively complex tasks. The design and development of a system architecture for image-guided surgery has been reported, demonstrating enhanced utilization of intraoperative CBCT in surgical applications with vastly different requirements. The system integrates C-arm CBCT with a broad variety of data sources in a modular fashion that streamlines the interface to application-specific tools, accommodates distinct workflow scenarios, and accelerates testing and translation of novel toolsets to clinical use. The modular architecture was shown to adapt to and satisfy the requirements of distinct surgical scenarios from a common code-base, leveraging software components arising from over a decade of effort within the imaging and computer-assisted interventions community.

Demons deformable registration of CT and cone-beam CT using an iterative intensity matching approach.

A method of intensity-based deformable registration of CT and cone-beam CT (CBCT) images is described, in which intensity correction occurs simultaneously within the iterative registration process. The method preserves the speed and simplicity of the popular Demons algorithm while providing robustness and accuracy in the presence of large mismatch between CT and CBCT voxel values ("intensity"). A variant of the Demons algorithm was developed in which an estimate of the relationship between CT and CBCT intensity values for specific materials in the image is computed at each iteration based on the set of currently overlapping voxels. This tissue-specific intensity correction is then used to estimate the registration output for that iteration and the process is repeated. The robustness of the method was tested in CBCT images of a cadaveric head exhibiting a broad range of simulated intensity variations associated with x-ray scatter, object truncation, and/or errors in the reconstruction algorithm. The accuracy of CT-CBCT registration was also measured in six real cases, exhibiting deformations ranging from simple to complex during surgery or radiotherapy guided by a CBCT-capable C-arm or linear accelerator, respectively. The iterative intensity matching approach was robust against all levels of intensity variation examined, including spatially varying errors in voxel value of a factor of 2 or more, as can be encountered in cases of high x-ray scatter. Registration accuracy without intensity matching degraded severely with increasing magnitude of intensity error and introduced image distortion. A single histogram match performed prior to registration alleviated some of these effects but was also prone to image distortion and was quantifiably less robust and accurate than the iterative approach. Within the six case registration accuracy study, iterative intensity matching Demons reduced mean TRE to (2.5 +/- 2.8) mm compared to (3.5 +/- 3.0) mm with rigid registration. A method was developed to iteratively correct CT-CBCT intensity disparity during Demons registration, enabling fast, intensity-based registration in CBCT-guided procedures such as surgery and radiotherapy, in which CBCT voxel values may be inaccurate. Accurate CT-CBCT registration in turn facilitates registration of multimodality preoperative image and planning data to intraoperative CBCT by way of the preoperative CT, thereby linking the intraoperative frame of reference to a wealth of preoperative information that could improve interventional guidance.

Minimally invasive superficial temporal artery to middle cerebral artery bypass through a minicraniotomy: benefit of three-dimensional virtual reality planning using magnetic resonance angiography

The aim of the authors in this study was to introduce a minimally invasive superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery by the preselection of appropriate donor and recipient branches in a 3D virtual reality setting based on 3-T MR angiography data. An STA-MCA anastomosis was performed in each of 5 patients. Before surgery, 3-T MR imaging was performed with 3D magnetization-prepared rapid acquisition gradient echo sequences, and a high-resolution CT 3D dataset was obtained. Image fusion and the construction of a 3D virtual reality model of each patient were completed. In the 3D virtual reality setting, the skin surface, skull surface, and extra- and intracranial arteries as well as the cortical brain surface could be displayed in detail. The surgical approach was successfully visualized in virtual reality. The anatomical relationship of structures of interest could be evaluated based on different values of translucency in all cases. The closest point of the appropriate donor branch of the STA and the most suitable recipient M(3) or M(4) segment could be calculated with high accuracy preoperatively and determined as the center point of the following minicraniotomy. Localization of the craniotomy and the skin incision on top of the STA branch was calculated with the system, and these data were transferred onto the patient's skin before surgery. In all cases the preselected arteries could be found intraoperatively in exact agreement with the preoperative planning data. Successful extracranial-intracranial bypass surgery was achieved without stereotactic neuronavigation via a preselected minimally invasive approach in all cases. Subsequent enlargement of the craniotomy was not necessary. Perioperative complications were not observed. All bypasses remained patent on follow-up. With the application of a 3D virtual reality planning system, the extent of skin incision and tissue trauma as well as the size of the bone flap was minimal. The closest point of the appropriate donor branch of the STA and the most suitable recipient M(3) or M(4) segment could be preoperatively determined with high accuracy so that the STA-MCA bypass could be safely and effectively performed through an optimally located minicraniotomy with a mean diameter of 22 mm without the need for stereotactic guidance.

Ein neues Verfahren zur bildfreien Kontrolle der postoperativen Genauigkeit navigiert gesetzter Implantate / A new X-ray-free measurement method for postoperative 3D-position analysis of navigated inserted implants

In this article a new X-ray-free measurement method for postoperative 3D-position analysis of dental implants is proposed. The advantage of this new method is the possibility of precise 3D comparison to preoperative planning data without the use of X-rays. Standard methods for postoperative implant analysis are performed manually on the basis of orthopantomography or computer tomography scans. The proposed method uses a navigation system and a specially designed measurement device. Analysis of the measurement data shows a mean position error of 0.2 mm +/-0.1 mm and a mean depth error of 0.4 mm +/- 0.3 mm. Thus, this method is suitable for postoperative analysis of the horizontal implant position and for comparison to preoperative planning

Comparison Between Hand Rasping and Robotic Milling for Stem Implantation in Cementless Total Hip Arthroplasty

We evaluated the effects of conventional hand rasping and robotic milling on the clinical and radiographic results of cementless total hip arthroplasty, with the same computed tomography (CT)–based 3-dimensional preoperative planning using a ROBODOC workstation (Integrated Surgical Systems, Davis, Calif). The robotic milling group consisted of 78 hips, and the hand-rasping group 78 hips. The radiographic findings from the preoperative planning and postoperative CT data were evaluated using the most accurate CT images reconstructed by the ROBODOC workstation. The robotic milling group showed significant superior Merle D'Aubigne hip score at 2 years. In the robotic milling group, there were no intraoperative femoral fractures, and a radiographically superior implant fit was obtained. Hand rasping had the potential to cause intraoperative femoral fractures, undersizing of the stem, unexpectedly higher vertical seating, and unexpected femoral anteversion causing inferior implant fit.

Iterative neuronavigation using 3D ultrasound. A feasibilty study

Intra-operative ultrasound (iUS) can generate 2D images in real-time as well as near real-time 3D datasets of the current situation during an intervention. Tracked ultrasound can locate the images in 3D space and relate them to patient, devices, and pre-operative planning data. Therefore, tracked US is an efficient means for controlling the validity of pre-operative planning, recognition of changes (brain shift) during the intervention, replanning of the operational path due to situational changes (iterative navigation), and finally, controlling the results (residual tumor). This paper describes a neuronavigation system exploiting this potential of interventional tracked US for permanent control of intervention progress and iterative adaptation of the planned procedure to the current situation.

Augmented reality and its future in orthopaedics.

Augmented reality is a display technique that combines supplemental information with the real world environment. Augmented reality systems are on the verge of being used everyday in medical training, preoperative planning, preoperative and intraoperative data visualization, and intraoperative tool guidance. The basic technologies of augmented reality are discussed, augmented reality systems currently being used in the medical domain are examined, and some future uses of these systems in orthopaedic applications are explored.